Hydraulic fluids

Abstract

The invention is concerned with an anhydrous oily lubricant, which is based on vegetable oils, which is substituted for mineral lubricant oils, and which, as its main component, contains triglycerides that are esters of saturated and/or unsaturated straight-chained C 10 to C 22 fatty acids and glycerol. The lubricant is characterized in that it contains at least 70 percent by weight of a triglyceride whose iodine number is at least 50 and no more than 125 and whose viscosity index is at least 190. As its basic component, instead of or along with the said triglyceride, the lubricant oil may also contain a polymer prepared by hot-polymerization out of the said triglyceride or out of a corresponding triglyceride. As additives, the lubricant oil may contain solvents, fatty-acid derivatives, in particular their metal salts, organic or inorganic, natural or synthetic polymers, and customary additives for lubricants.

What is claimed is: 
     
       1. A basic hydraulic fluid composition consisting of: 85to 99 percent by weight of at least one natural triglyceride which is an ester of a straight-chain C 10  to C 22  fatty acid and glycerol, which triglyceride has an iodine number of at least 50 and not more than 128,   the balance being selected from at least two of the following groups: Group 1: Hindered phenolics, aromatic amines, selected from the group consisting of 2,6-di-tert-butyl-4-methyl phenol; 2'2-methylenebis(4-methyl-6-tert-butylphenol); N,N'di-sec-butyl-p-phenylene-diamine; alkylated diphenyl amine; alkylated phenyl-alfa-napthylamine   Group 2: Metal salts of dithioacids, phosphites, sulfides, selected from the group consisting of zinc dialkyldithiophosphates; tris(noylphenyl)phosphite; dilauryl thiodipropionate   Group 3: Amides, non aromatic amines, hydrazines, triazols, selected from the group consisting of N,N'-diethyl-N,N'-diphenyloxamide; N,N'-disalicylidene-1,2-propenylenediamine; N,N'-bis(beta-3,5-ditertbutyl-4-hydroxyphenyl-propiono)hydrazide.     
     
     
       2. A base hydraulic fluid composition according to the claim 1 wherein the triglyceride is of oleic-acid-linoleic-acid type and contains saturated fatty acids of not more than 20 percent by weight calculated on the quantity of fatty acid esterified with glycerol. 
     
     
       3. A base hydraulic fluid composition according to the claim 1 or 2, wherein the triglyceride consists of rape seed oil. 
     
     
       4. A hydraulic fluid having the following composition:   ______________________________________                                    
Refined rapeseed oil,                                                     
                  96.5    percent by weight                               
Zn--dialkyldithiophosphate                                                
                  1.5     percent by weight                               
(Anglamol ® 75),                                                      
Tertiary-butyl phenol deri-                                               
                  2.0     percent by weight                               
vative (Hitec ® 4735),                                                
______________________________________                                    
     
     
     
       5. A hydraulic fluid having the following composition:   ______________________________________                                    
Refined rapeseed oil,                                                     
                   98.9    percent by weight                              
Amino phosphate derivative                                                
                   0.5     percent by weight                              
(Irgalube ® 349),                                                     
2,6-di-tert.-butyl-4-                                                     
                   0.5     percent by weight                              
methylphenol (Additin ® 10),                                          
Triazole derivative                                                       
                   0.05    percent by weight                              
(Reomet ® 39),                                                        
N--acyl-sarcosine  0.05    2                                              
(Sarkosyl ® O)                                                        
______________________________________                                    
     
     
     
       6. A hydraulic fluid based on the composition defined in claim 1, wherein the fluid in addition contains at least one: demulsifier, selected from the group consisting of: heavy metal soaps; Ca dn Mg sulphonates.   
     
     
       7. A hydraulic fluid based on the composition defined in claim 1, wherein the fluid in addition contains at least one: boundary lubrication additive, selected from the group consisting of: metal dialkyl dithiophosphates; metal diaryl dithiophosphates; metal dialkyl dithocarbamates; alkyl phosphates; phosphorized fats and olefins; sulfurized fats and fat derivatives chlorinated fats and fat derivatives.   
     
     
       8. A hydraulic fluid based on the composition defined in claim 1, wherein the fluid in addition contains at least one: corrosion inhibitor, selected from the group consisting of: metal sulfonates; acid phosphate esters; amines; alkyl succinic acids.   
     
     
       9. A hydraulic fluid based on the composition defined in claim 1, wherein the fluid in addition contains at least one: VI improver, selected from the group consisting of: polymethacrylates; styrene butadiene copolymers; polyisobutylenes.   
     
     
       10. A hydraulic fluid based on the composition defined in claim 1, wherein the fluid in addition contains at least one: pour point depressant, selected from the group consisting of: chlorinated polymers; alkylated phenol polymers; polymethacrylates.   
     
     
       11. A hydraulic fluid based on the composition defined in claim 1, wherein the fluid in addition contains at least one: foam decomposer, selected from the group consisting of: polysiloxanes; polyacrylates.